Original articlesAccuracy of subacromial injection: Anterolateral versus posterior approach
Section snippets
Materials and methods
Ten pairs of fresh-frozen cadaveric shoulders (mean age, 73.6 years; age range, 52–90 years) were thawed to room temperature until soft tissues were compliant and mounted in an upright position, clamped at the medial scapula. Each shoulder was injected with 2 mL of radiographic contrast in the subacromial space via anterolateral and posterior approaches by use of a 21-gauge, 1.5-inch (3.8-cm) needle, with fluoroscopic evaluation after each technique. Each shoulder was thus injected twice, once
Anterolateral approach
Subjective grading (Table I) for the anterolateral approach consisted of a grade 3 for 15 injections, grade 2 for 3 injections, and grade 1 for 2 injections. Of the 15 grade 3 injections (confident of accuracy), 12 (80%) were accurate on dissection. The other 3 injections that had been given a grade of 3 were inaccurate, as a result of placement of the injected material medial to the medial boundary of the bursa. Of the 3 injections given a grade of 2, 2 were accurate (67%). Of the two
Discussion
Accuracy of subacromial injection was comparable whether the anterolateral approach (60% accuracy) or posterior approach (80% accuracy) was used, by use of dissection as the gold standard for evaluation. Power did not reach .80, and over 100 specimens would have been required to meet this threshold. The anterolateral accuracy rate is slightly less than that in 2 recent studies, 7, 9 which demonstrated rates of 70% to 83% via the anterolateral approach, and is higher than the rate of 29%
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